The application of braces in your mouth will make it kind of sore and can make you uneasy. However, the discomfort does not last for long and soon you will adapt to having them on and perform your duties normally. Consult a qualified dentist to get more informed on this.
the first 2-3 days hurt, but not my teeth, the insides of my lips because of the metal. After that you don't even notice them, tighting them didn't hurt me, I didn't notice. The first day I had them I tried to eat bagel, it totally failed, haha.
no it doesnt hurt at all. The worst part is the impressions. They put gooey stuff in your mouth so that they can fit a retainer but I just got mine off and it hurts more to get them off then to get them on.